AN SMA FOUND HIMSELF IN UNFORECASTED ICING.

Narrative

I WAS ON AN INST FLT FROM FLD DIRECT STE; RADAR VECTORS TO RCX. CRUISING AT 4000 FT ON TOP OF THE CLOUDS AT 38 DEG F; APPROX 10 DME NW OF STE; CTR INFORMED ME THEY LOST RADAR CONTACT AND TO RPT ABEAM MDZ. APPROX 25 DME NW OF STE I ENCOUNTERED HIGHER CEILINGS OF APPROX 6500 FT. AS I ENTERED THE CLOUDS LEVEL AT 4000 FT; I NOTICED THAT I WAS SEEING MOISTURE DEVELOPING ON THE WINGS AND WINDSHIELD; AS WELL AS THE TEMP WAS LOWERING QUICKLY BELOW FREEZING. I NOTIFIED CTR THAT I WAS BEGINNING TO PICK UP SOME ICE. I ASKED FOR LOWER HOPING TO EITHER FIND HIGHER TEMPS OR VFR CONDITIONS; BUT CTR COULD ONLY LET ME DOWN TO 3600 FT. I LOWERED TO 3600 FT; WAS STILL PICKING UP ICE; CTR WANTED ME TO DO THE NDB APCH INTO MDZ; BUT I DECLINED AS I WAS NOT PREPARED FOR THE APCH. I QUICKLY DECIDED AND ANNOUNCED I WAS DOING A 180 DEG TURN AND CLBING. CTR CLRED ME TO DO WHATEVER I NEEDED TO DO. I FIREWALLED THROTTLE; MIXTURE AND PROP; WAS ABLE TO CLB TO CLR CONDITIONS ABOVE 6500 FT; LEVELED AT 7500 FT AND 38 DEG F TEMPS. AFTER 5-10 MINS; ALL THE ICE BURNED OFF; CTR GAVE ME A 7000-8000 FT BLOCK ALT AND ASKED FOR MY INTENTIONS. AFTER CONTACTING FLT WATCH; I DECIDED TO PROCEED TO RCX AND NEGOTIATED WITH CTR TO STAY AT 7500 FT. THEY CLRED ME FOR THE APCH; NO ICE ENCOUNTERED. IN RETROSPECT; DUE TO THE 38 DEG F TEMP PRIOR TO ENTERING THE CLOUDS; I WAS VERY SURPRISED HOW QUICKLY THE TEMP DROPPED IN THE CLOUDS; SOMETHING I WILL NEVER FORGET TO ANTICIPATE IN THE FUTURE. ALSO TO BE MORE PREPARED TO MAKE AN EMER APCH IN THE FUTURE.